Roger - I would be interested in your corner spline description. I have done some boxes but not with mitered corners.
Would the spline apply to bigger picture frames as well?
To answer the last question first....
Yes, splines can be done on picture frames and I use them quite often my self. They do add a lot of strength to mitered corners on anything. The extra glue surface as well as the cross grain of the spline itself makes for a very strong joint for miteres. I also use half lap/mitered corners which are a bit tricky to make but, make for "bomb proof" joints on frames.
As to how to add splines to mitered corners on boxes, there is more than one way to skin that cat, and the way I do it is not necessarily the RIGHT way it is just MY way. They can be done with a router, a router in a table, or my way, on the table saw as well as with a hand saw and a GOOD eye.
My method requires another jig to be made for the table saw. The jig is as simple as the miter jig that started this whole post.
(I had better interject here and say....Glue up the box FIRST and give the glue time to cure before handing too much and make sure it is good and square before cutting spline slots.)
To get the idea, take your miter jig, stand it on edge so that the legs form a "V" to the saw table...Get the idea? Now build another jig very similar to it only make the legs closer to 12" high (really 8" is enough for most boxes) and 8"-12" long and trim the bottom of the "V" to leave an opening flush at the table surface. Using the saw fence and a few calculations for placement of the splines, nest the box in the "V" at the 45 degree angle and make a cut. OH YEA! You also need to calculate the height of the blade so that you don't cut into the interior of the box but, you do need as much depth as you can get. I find that if I'm using 1/2" side stock, 1/2" blade height is about right. The distance right at the miter will be greater than 1/2" so you will have some meat left for a good inside corner for looks.
The other thing that I think is important is to use a dado blade to cut the slots so that you don't have to move the fence to get a wider cut for the spline. I have a set of "Freud" box joint blades that will make a 1/4" kerf or a 3/8" kerf depending on how I stack them but, the two outside blades of a dado set will get you a 1/4" cut also or you can even stack a few more blades on for an even wider cut for wider splines.
Splines...That is another thing....I like to use contrasting wood for visual appearance (except for picture frames, there I use the same wood so it WON'T contrast) Just rip a strip of the contrasting wood to 1/4" or however wide your slots are and make sure it fits in the miter slots of the box nice and snug and and several inches long. Depending on how many splines you need of course. I sometimes will glue one end of the strip in a slot, and trim it off fairly flush with the side of the box glue it again in the next, trim and keep on keeping on until all the slots are filled. Or you can cut them into short pieces and glue all of them in at once and then flush trim all the splines at once.If you give the glue just a few minutes to start to set up, you can handle the job in fairly short order without messing it up too bad. Then the next day (after the glue has set up good) the sanding begins!
Placement of the splines is more a matter of personal taste. I like to use at least three splines per corner. Usually one in the center and one about 1-1/2"- 2" from the top and bottom. I have used as many as six per corner on taller boxes but, it soon becomes too busy and you may as well use finger joints after that point.
I might also add......You will have to make another (or remake) your jig after cutting splines in eight or ten boxes of different sizes as you will wear out the bottom of the jig from using different spacings for the splines..... DAMHIKT
.....(Don't ask me how I know that)
I hope this helps you or anyone else that wants to get into making boxes. If you need further explanation don't hesitate to ask me, I'm here to help.
Rog
